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| author | Austin Clements <austin@google.com> | 2015-12-17 15:35:49 -0800 |
|---|---|---|
| committer | Austin Clements <austin@google.com> | 2015-12-18 17:08:32 +0000 |
| commit | a4a57bb4f9a7d4d2d7f4cbe373ab446d73c25966 (patch) | |
| tree | 3bccdf0b4fbceff43d80840f8b30729a447b9d48 /src | |
| parent | 90a68935733ef37d41cb520ffeb56f196a356811 (diff) | |
| download | go-a4a57bb4f9a7d4d2d7f4cbe373ab446d73c25966.tar.xz | |
runtime: prevent race between setNextBarrierPC and sigprof
Currently, setNextBarrierPC manipulates the stack barriers without
acquiring the stack barrier lock. This is mostly okay because
setNextBarrierPC also runs synchronously on the G and prevents safe
points, but this doesn't prevent a sigprof from occurring during a
setNextBarrierPC and performing a traceback.
Given that setNextBarrierPC simply sets one entry in the stack barrier
array, this is almost certainly safe in reality. However, given that
this depends on a subtle argument, which may not hold in the future,
and that setNextBarrierPC almost never happens, making it nowhere near
performance-critical, we can simply acquire the stack barrier lock and
be sure that the synchronization will work.
Updates #12528. For 1.5.3.
Change-Id: Ife696e10d969f190157eb1cbe762a2de2ebce079
Reviewed-on: https://go-review.googlesource.com/18022
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/mstkbar.go | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/src/runtime/mstkbar.go b/src/runtime/mstkbar.go index 6b4fc8d4a6..7d7235d259 100644 --- a/src/runtime/mstkbar.go +++ b/src/runtime/mstkbar.go @@ -305,7 +305,9 @@ func nextBarrierPC() uintptr { //go:nosplit func setNextBarrierPC(pc uintptr) { gp := getg() + gcLockStackBarriers(gp) gp.stkbar[gp.stkbarPos].savedLRVal = pc + gcUnlockStackBarriers(gp) } // gcLockStackBarriers synchronizes with tracebacks of gp's stack |